Many conventional medical monitors require attachment of a sensor to a patient in order to detect physiologic signals from the patient and transmit detected signals through a cable to the monitor. These monitors process the received signals and determine vital signs such as the patient's pulse rate, respiration rate, and arterial oxygen saturation. An example of a prior art monitoring system 100 is shown in FIG. 1. The system 100 includes a monitor 110 and a sensor 112 connected to the monitor 110 by a cable 114. In the example of FIG. 1, the monitor 110 is a pulse oximeter, and the sensor 112 is a finger sensor including two light emitters and a photodetector. The sensor 112 emits light into the patient's finger, detects light transmitted through the patient's finger, and transmits the detected light signal through the cable 114 to the monitor 110. The monitor 110 includes a processor that processes the signal, determines vital signs (including pulse rate, respiration rate, and arterial oxygen saturation), and displays them on an integrated display 116.
Other monitoring systems include other types of monitors and sensors, such as electroencephalogram (EEG) sensors, blood pressure cuffs, temperature probes, and others.
Many of these conventional monitors require some type of cable or wire, such as cable 114 in FIG. 1, physically connecting the patient to the monitor. As a result, the patient is effectively tethered to the monitor, which can limit the patient's movement around a hospital room, restrict even simple activities such as writing or eating, and prevent easy transfer of the patient to different locations in the hospital without either disconnecting and connecting new monitors, or moving the monitor with the patient.
Some wireless, wearable sensors have been developed, such as wireless EEG patches and wireless pulse oximetry sensors. Although these sensors improve patient mobility, they introduce new problems such as battery consumption, infection risk from re-use on sequential patients, high cost, and bulky designs that detract from patient compliance and comfort.
Video-based monitoring is a new field of patient monitoring that uses a remote video camera to detect physical attributes of the patient. This type of monitoring may also be called “non-contact” monitoring in reference to the remote video sensor, which does not contact the patient. The remainder of this disclosure offers solutions and improvements in this new field.